1. Field of the Invention
The present invention relates to an operation device that generates an operation signal by a switch input, and in particular, to an operation device that can increase safety by determining a failure more reliably.
2. Description of the Related Art
A switch input for ON/OFF of the contact of an electrical circuit is used in an operation device for controlling various apparatuses. For example, a switch input is used in an operation device for vehicles that is used to operate a vehicle transmission for driving control of the vehicle with an electrical operation signal.
Japanese Patent No. 3912344 discloses a control device 200 of an automatic transmission with a manual mode that allows manual mode switching or manual shift operation. FIG. 26 is a schematic diagram of the control device 200 disclosed in Japanese Patent No. 3912344.
As shown in FIG. 26, an automatic transmission 220 includes an automatic transmission mode and a manual mode, and changes the gear ratio according to the command of an electrical operation signal from a controller 201. The controller 201 is mainly configured by a microcomputer. The controller 201 reads signals from a mode change switch 203, an upshift switch 204, a downshift switch 205, and a selector switch 202 according to the operation of a shift lever 221 operated by the driver and determines a gear ratio based on the shift map set in advance, and transmits an instruction based on the determination to the automatic transmission 220. The mode change switch 203 for setting the manual mode, the upshift switch 204, and the downshift switch 205 are formed by a push switch including a normally open contact and a normally closed contact. By the operation of pressing the push switch, for example, a sliding portion having a movable contact moves to come into contact with or be separated from the fixed contact.
If the switches 203 to 205 are normal, only one output is necessarily turned on in response to each operation including non-operation. With the normally closed side of the downshift switch 205 as a monitor signal line 210, a signal is input to the controller 201. Accordingly, if other signals become ON when a monitor signal is ON, it can be determined that the contact has been fixed in any one of the switches 203 to 205. As a result, it is possible to detect an abnormality due to fixation. When inputs from all signal lines 207 to 210 become OFF, it can be determined that disconnection has occurred in any one of the switches 203 to 205 and the circuit.
If one of the signals is ON, it is determined that the switches 203 to 205 and the circuit are normal without disconnection and fixation, and normal control to perform a shift according to the operation is performed. On the other hand, when an abnormal pattern continues to exceed a predetermined value (predetermined time), it is determined that an abnormality has occurred in the switches 203 to 205 or the circuit.
In addition, although the specific configuration of the selector switch 202 is not disclosed in Japanese Patent No. 3912344, it is possible to use a shift lever position detecting switch (inhibitor switch) of the shift lever 221 operated by the driver. In addition, since the selector switch 202 serves to only transmit an electrical operation signal to the controller 201, a switch input can be applied instead of the shift lever 221.
However, in each switch input, there is a transient period in which a normally open contact and a normally closed contact are in an ON state or in an OFF state at the same time. In a switch structure where the movable contact is in contact with the fixed contact, there is rattling between the constituent members. Accordingly, in a half-pressed state of the push switch, there is a possibility that both contacts will be turned on or off. Therefore, in the control device 200 in the related art, it has been difficult to determine whether both the contacts are in an ON state or in an OFF state due to the transient period or the half-pressed state or both the contacts are in an ON state or in an OFF state due to the fixation of any one of the contacts. This problem is the same for a switch structure including two normally open contacts.